Carburetor



June 24, 1930.

M. E. CHANDLER CARBURETOR Filed Dec. 1'7, 1925 dune ftd, ldd@ MLTN ld. CHANDLER, @F GHCG, XLLENOIS, ASSEGNOR T0 STROMBER@ MOTQR .EEVEGES GQ., DI? UHECG, LLLlilGllS, A 'CORPlEt/ATIGN @F LLHQIS ARBURETR Application :tied :December i7, 1925. Serial No. 75,951.

ll/fy invention relates to carburetors andv the object is to provide more certain and reliable adjustment for serving an engine for idling operation and to increase the range for such operation.

In prior arrangements a single idling jet connects with the carbureting `chamber of the carburetor to co-operate with the edge of the throttle valve, but such arrangement has many disadvantages. For. a low idle operation it is often necessary to have the throttle closed to within a very small crack, and then a variation of a few thousandths of an inch up or down of the position of the single jet would maire a perceptible difference. Great accuracy of manufacture is, therefore, necessary to insure proper` positioning of the throttle valve relative to the single jet to get reliable results.

With such single jet arrangement the range of operation is also limited. It is sometimes necessary that the idling fuel system cover a range from two or three miles per hour up to twelve miles per hour and with the single jet arrangement a setting that will be correct for the demand of the engine at extremely low idling operation is often extremely lean at the higher end of the idling range just before the main carburetor jet begins to deliver fuel.

My improved arrangement overcomes the above disadvantages as I provide, in addition to the throttle valve co-operating jet, a definite, fixed size jet above the throttle and exposed at all times to the full suction eiect in the engine manifold. rlhe jet which cooperates with the throttle is adapted to be entirely closed when the throttle is fully closed, and this jet becomes in edect a secondary nozzle when it comes into operation as the throttle is opened. With such two outlets or jets the idlin performance of the carburetor will be muc less variable. rlhe range of adjustment is also increased so that there will be sudicientand adequate fuel supplied to the engine from extreme low idle operation up to a speed of say twelve miles per hour. The lowest idling speed mixture through the upper iixed jet is nrst set by means of the air bleed adjustment and then by increasing or'decreasing the size of the lower jet, which co-operates with the throttle valve, the desired mixture is obtained for the higher speeds. I

For contributing to a uniform idling condition in different carburetors and for modifying the idling mixture range, l have found it advantageous to provide a small hole through the throttle valve adjacent to the idling discharge outlet. With such arrangement the throttle valve can be entirely closed, thus cutting oil any gasoline feed from the lower idllng discharge opening and requirlng less air to be bled into the idling stream, and thus assuring a richer mixture at higher speeds when the throttle is opened.

On the drawings Figure l is a side elevational view partly in vertical diametral section of a carburetor embodying my improvement;

2 is a sectional view on plane 22 of ig.

The plain tube design, of carburetor illustrated is shown merely as being representative of a class of carburetors employing idling jets, it being understood that the invention is not restricted thereto, but is applicable to other types and designs of carburetors requiring regulation of the idling mixture. The tubular housing 10 has the usual air inlet horn l1, the air dow through which is controlled by a choker valve 12, while the mixture outlet 13 is controlled b a butterfly vvalve 14 mounted on the sha' t 15. The doat chamber 16 supplies fuel to a nozzle structure17 through ya passageway 18, the nozzle discharging into the small venturi 19, which in turn discharges into the large venturi 20 mounted in the carburetor tube or body 10 below the throttle valve.

The vertical idling passageway 21 receives fuel through a metering passageway 22 from the duct 23, which communicates with the bore of the nozzle structure 17. The accelerating well 2d is supplied with fuel through the passageway 25 and at the proper time discharges into the small venturi 19 through the nozzle passageway 26. At its upper end the well communicatesv through the port 27 with the outlet passageway 13 iii) above the throttle, and the well is air-bled through the inlet 28.

At its upper end the idling fuel supply passageway 21 communicates with the mixture outlet passageway 13 through an outlet opening or jet 29, this opening being above the throttle valve. Below this opening is the secondary opening 30, whose inner end is bridged by the throttle valve when such valve is in closed or practically closed position. Below these idling fuel inlets an air bleed passageway 31 communicates with the idling fuel passageway 21, this air bleed passageway receiving air supply through the passageway 32 through the venturi which communicates with the interior of the carburetor body and the air therein. A needle valve 33, adjustable within the fitting 34.-, controls the volume of air dow through the bleeder passageway 31.

The upper outlet 29 may be considered as the main outlet for the idling fuel supply and the lower passageway 30 may be considered as a secondary outlet or nozzle which, by its co-operation with the throttle valve, modifies or adds to the fuel supply through the mainoutlet. If only the lower outlet were used, and for low idle operation it would become necessary to have the throttle valve closed up to a very small crevice, a very small variation up or down in the position of the single outlet might make a perceptible difference, and extreme care and accuracy would be necessary in the manufacture of the carburetor. However, by providing the definite fixed size main o ening or outlet above the throttle valve, ully connected at all times with the engine manifold, a slight variation in the position of the secondary outlet relative to the throttle valve would not be of such great importance.

In adjusting the carburetor, the throttle valve is closed, closing the outlet 30, and then the air bleed valve 33 is adjusted for extreme low idle operation. As the throttle is now gradually opened for higher speeds, the secondary outlet or nozzle 30 becomes more e'ective, as it is more exposed to the engine suction effect and to the flow of air between the throttle valve and the outlet end, the supply to the main outlet 29 remaining practically undiminished throughout a considerable ran e of opening movement of the throttle va ve. It may be that the main carburetor nozzle 17 will not come into operation until comparatively considerable speed, say twelve miles per hour, is reached and the two idling outlets must co-operate and function to insure propermixture up to such increased speeds from the lowest idling speed of, say, two or three miles per hour. By adjusting the size of the secondary outlet 30 and the air bleed passageway 31, the proper mixture throughanything, on the rich side.

.out this range can be readily obtained. If, when setting for the lowest idling speed mixture, by means of the air bleed valve 33, it is found that the mixture ,is too lean for the higher values of the speed range, then the passageway 30 can be properly enlarged, and if the mixture at such higher speeds is found to be too rich, then such secondary passageway is made smaller.

When the throttle valve is suddenly opened for sudden acceleration, there is a small increment of time before the carburetor main jet and accelerating system begin to deliver fuel, and to avoid hesitation of the engine at this time, it is necessary that the previous idling mixture be not lean, but if Therefore during the most difficult part of the engine range of operation my improved arrangement will assure adequate and suicient combustion mixture supply to the engine.

I have found it advantageous to provide an air passageway'or hole `35 through the throttle valve adjacent the idling discharge openings. Such arrangement will give extremely steady condition for low idling operation as the throttle valve can be entirely closed, and air passageway between the throttle valve and secondary outlet, which passageway on account of mechanical irregularities mayor may not be proper, need not be depended upon for assisting or modifying the service through the main outlet 29. Such entire closure of the throttle valve will also entirely close the secondary outlet or nozzle 30 to the flow of fuel, as previously noted, and this, together with the flow of air through the hole 35, will make it ossible to materially reduce the amount o air by wa of the bleeder valve 33 as compared to car uretors not having an unobstructed air opening through the throttle valve. As a result of this reduced air bleed adjustment by the valve 33 there will be a richer mixture as the throttle valve is opened for higher speed of idling. As the throttle valve is opened and the secondary outlet 30 exposed there will be additional fuel discharged through such outlet, and by placing the hole 35 adjacent to the idling outlets the air flowin through the hole vcan thoroughly mix with the fuel discharged from the outlets and so compensate for the reduced air bleed adjustment of the valve 33. The air hole arrangement which I have shown zfor the throttle `valve co-operates with the idling outlets'to produce the effect 'of contributing to a uniform idling condition in different carburetors and of modifying the idling mixture range. In the type of plain tube carburetor shown, such range may be from three to twelve miles per hour or even higher and requires practically a mechanical control of the mixture. As the throttle lpasses between the low and high positions the manifold vacuum does not in-y crease, but, if anything, decreases at the high end of the range, and it is necessary in the face of such decreasing manifold vacuum to increase the fuel delivery from the idle jet. -This as has been explained is accomplished by my improved arran ement.

Having described my invention, claim the following :f

In a carburetor, in combination, a carbureting chamber having an air inlet, a throttle valve in said chamber, the carburetor having an-idling fuel passageway and two outlets therefrom to the carbureting chamber, one of said outlets being of constant effective area and disposed outwardly beyond the valve when said valve is closed, the other outlet being closed by the valve when the latter is in closed position and uncovered as the valve is opened, said valve having an opening unobstructed in all positions of the valve and disposed to cause air flowing through said opening when the valve is closed,to intersect the fuel spray ejected from the first mentioned outlet.

In witness whereof, I hereunto subscribe my name this 15th day of December, 1925.

yMILTON E. CHANDLER. 

